Process of treating ores.



I R.- GAHL. PROCESS OF TREATING ORES. APPLICATION rum) we. 29, 1911.

Patented Apr. 2. 1912.

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Zdriirzesa es.-

UNITED STATES E T orr on RUDOLF GAHL, or MOBENCI,.ARIZONA.-

PROCESS OF TREATING ORES.

Specification of Letters Patent.

Patented A r. 2, 1912.

. Application med August 29, 1311. Serial No. 646,684.

To all whom it may concern.

. Be it known that I, RUDOLF GA'HL, a sub-' 'ject of the Emperor-ofGermany, residing at Morenci. in the county of Greenlee and State ofArizona, have invented certain new and useful Improvements in Processesof Treating Ores, of which the following is a specification.

This invention relates to processes of. treating ores, the object "ofthe-invention being the provision of an economical and eflicient processfor the preparation of metal-bearing solutions from which the metals maybe recovered by precipitation.

v The invention is applicable with particular advantages to thetreatment of copper ores, but-is likewise applicable to other ma-'terialsnas for example the recovery of "gold and silver by thecyanid'process.

The extremely finely divided ore formed by crushing and grinding andtermed slime is preeminent-1y adapted for treat- -ment n accordancew1t-h my lnventlon, al-

though coarser materials, as for instance fine sands or mixtures ofsands'andslimes may also be treated advantageously.

Inl'eachmg fine ores, one of the pr1nc1pal difficulties encountered isinseparating the liquid from the solidmatter. Filtering has come intoextensive use of late, but in addi-- (ion to its high cost it presentspractical difficulties in the treatment of certain classes of ore.Furtl1ermore,'theconstruction of filter presses and vacuum filters whichwill withstand the corrosive action The invention will be explained byrefer-,- ence to the accompanying draw1ngs,.wl1ere- Figures land 2represent in a diagrammatic' manner the sequence of operations inprocesses of continuous decantation; and- Big; 3 indicates the sequencepreferably employed "in accordance with the present improvaaent. a Incarrying out a continuous deeantation According to this tr atment the.process,.the pulp, after having been treated with "a suitable leachingsolution, is sepa rated from a large portion of the solution by thefirst settling. The thickened pulp "is then mixed with a solutioncontaining a lower Percentage of the economic metal than the solutionfirst decanted, and is transferred to another settling tank. Thisoperation is repeated often enough to reduce as far as may be consideredpracticable the content of economic metal in the solution coveringthepulp.

"Ignoring in the interest of simplicity the existence of means forefiectingthe mixture, "each settling tank will receive two feedproducts,]nam,ely, thickened pulp and solution, and will yield twoproducts which are likewise thickened pulp and solution. Figs. 1 and 2of the drawings represent simple arrangements for accomplishing thisresult. In said figures, D, 'D represent means for settling, hereinafterreferred to-as settling tanks; and P, P represent meansfor-precipitating metal, hereinafter called precipitatxin'g plants.Means for mixing,agitating,

aerating} etc.,, are commonly used but may be here left out ofconsideration In all "figures the solid lines represent the direction offlow of thickened pulp; while the dotted lines represent thedirection ofHow of the solution orsupernatant liquid.

' In the processindicatedby Fig. lathe decanted solution from each tankD is sent to a corresponding precipitating plant P, and thence returnedto the head of the settling tank to bemixed with the feed. In theprocess indicatedgby Fig. 2 the liquid decanted from the firstsettlingtankD passes through a precipitating plant to the secondsettling tank; the liquid decanted from the second tank passes through aprecipitating plant to-the third settling tank, and so on, while liquiddecanted from the last tank is returned to the head. ofthe first tankafter having passed throu h aprecipitating plant. 4

It will be observed t ataccording to each of these diagrams aprecipitating plant is re-' quired in connection witheach settlmgtank.

' I have found that results superiorin efliw 'ciency and economy ofextractlon and with reduced consumption of solvent are secured byfollowing the method i1idicated Fig. attes" de- 'i afl d r e m 'l e' lato the last but one, While canted frames tank s ne te ses imhead tank ofthe series. In other words,

mediately preceding it in series, and so 'on throughout the series. Thesolution de-' canted from the first tank'in Series is sent to aprecipitating plant and then returned to the. last tank. Meantime thethickened from the first tank .to the last.

This system, in addition to the special advantages hereinafterpointedout, possesses.

the obvious advantage that oneprecipitating plant only is required fortheseris of decanting vessels, a thorough washing being neverthelesssecured. In proceeding according to this arrangement it ishighly'advantageous to introduce the. leaching agent or solvent, not atthe head of, the system as has always'beenpracticed heretofore, but atan intermediate point, for instance at the point indicated by [Xin Fi3.- It is preferable to introduce the leac ing'agent ata point where thepulp contains auninimum of water, as a higher extraction is thus ob-.tained than when the agent is mixed with a more dilute pulp. 7

By introducing the leaching agent at an intermediate point the followingadvantages a single operation, even though tion may be greatly prolongeare gained: (1.) It is a' known fact that leaching is far from beingperfect when .carriedout in The leach. ing agentis never completelyconsumed, but a certain-percentage remains unchanged in the leachingtank, as determined by the laws of chemical mass action. According tothe' present invention the undecoinposed portion of the leaching agentis largely transferred with the solution to the preceding tank(.counting in the order of the flow of the thickened pulp). There itencounters fresh pulp on which it exercises its solvent 'eflect. Anyleaching agent which may yet remain unchanged finds another opportunityfor exercising its solvent action in the by introducing the leachingagent at some point below. the head' ofthe system the advantage isgained'that the leaching takes place by the action of a counter current,nearly exhausted pulp being treated by fresh leaching liquor, while.fresh pulp is i brought in contact with partly exhausted leachingliquorQ. At the same time the liquid flowing from the precipitatingplant is avail able for the thoroughwashing of the pulp in the lasttanks of the series.

(2.) In the case of copper ores treated with solutions containing ironsalts with subsequent precipitation by iron, a further advantage resultsfrom conducting-the flow as indicated in Fig. 3. As mentioned above,

the partly exhausted leaching solution is brought into contact'withfresh ore and theferric salts are thereby transformed into ferrous saltsand the consumption of metal- I tially avoided. pulp passes regularlythrough the series this opera lic iron is reduced nearly to thetheoretical limit. This is for the reason that the loss of .ironresulting from the passage of ferric salts to the precipitating plant issubstan- (.3.) An additional advantage is-secured in case thecirculating pulp is heated for the purpose of improvin the extractlon.Heat, for instance in the orm of steam,'is preferably applied eitheratthe same point as the leachin ate, point 0 the plant. As may be seenby tracing the manner in which the heat thus introduced distributesitself over the system, the advantages are gained, that the heat isapplied where it is most needed,

namely, in the final leaching, that it is used; to preheat the inflowingpulp; and that the loss of heat due to'theoutflow of heated pulp isrelatively low, as the temperaturedecreases toward the end of thesystem. i

It will be understood that the flow of pulp '75. agent or at anotherintermediand liquid through the system may be either continuous orintermittent as may be desired. It will be observed that whereas theflow of thickened pulp and supernatant liquid may be in the samedirection through individualvessels of the series, their resultant flowthrough the series of vesselsis in opposite directions.

It is to be understood that the mode of application of the invention maybe variously modified ,without departing from the and solution. It is,however, not necessary that the solutions should be perfectly free fromsolid material, but merelythat the solution which flows to theprecipitating plant should be reasonably clear. In case t e overflowfrom the first settling tank 1s not sufiiciently clear, its action maybe supplemented by a clarifying tank or filter.

The diagrammatic illustrations are based on the assumption that thethickened pulp runs by gravity from tank to tank, while thesupernatantsolutions are pumped from tank to tank. This arrangement may bereversed, or the tanks may be placedpn virtually level ound and thecirculation both of the-th ckened pulp and solution 'may -beawfiimpllshed by pumping.

,1.The process of treating oresby decantation to prepare metal-bearing;solutions, which consists in causing thickened pulp and a supernatantliquid to traverse a series of decanting vessels in resultantly oppositedirections, and introducing a leaching agent at a. point intermediatethe ends of the series.

'2. The process of treating ores by decantation to prepare metal-bearingsolutions, which coilsists in causing thickened pulp and a supernatantliquid to traverse a series .of decanting-vessels in. resultantlyopposite directions, and introducing a leaching agent and applying heatat a point or points intermedlate the. ends of the series.

3. The process of treating ores to recover values therefrom, whichconsists in. causing thickened pulp and a supernatant liquid to traversea series of decanting vessels in resultantly opposite directlons,introducing a leaching agent at. a pointintermediate the ends oftheseries, and precipitating-the values from the outflowing liquid.

' 4. The process of treating ores to recover valuestherefrom, whichconsists in causing thlckenedpulp and a supernatant llquid to traversea-series of decanting vessels in resultantly opposite directions,introducing a leaching agent at a point intermediate the ends of theseries, precipitating the-values from the outflowing liquid andreturning the same to the opposite end of the series.

In testimony whereof, I a-fiix lny signafive cents each, by addressingthe Commissioner of Patents, I Washington, I). G.

